package com.problemproject.dome.encryption;


import android.util.Log;

import java.math.BigInteger;
import java.security.Key;
import java.security.KeyFactory;

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;

import java.security.SecureRandom;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;

/**
 * 创建时间 : 2022/4/11
 * 描述：
 */

public class RSAUtils {
        public static String PUBLICKEY = "";//你的publicbey
        public static String PRIVATEKEY = "";//你的privatekey

        /**
         * 指定key的大小
         */
        private static int KEYSIZE = 1024;

        /**
         * 生成密钥对
         */
        public static Map<String, String> generateKeyPair() throws Exception {
            /** RSA算法要求有一个可信任的随机数源 */
            SecureRandom sr = new SecureRandom();
            /** 为RSA算法创建一个KeyPairGenerator对象 */
            KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
            /** 利用上面的随机数据源初始化这个KeyPairGenerator对象 */
            kpg.initialize(KEYSIZE, sr);
            /** 生成密匙对 */
            KeyPair kp = kpg.generateKeyPair();
            /** 得到公钥 */
            Key publicKey = kp.getPublic();
            byte[] publicKeyBytes = publicKey.getEncoded();
            String pub = new String(Base64Utils.encodeBase64(publicKeyBytes),
                    ConfigureEncryptAndDecrypt.CHAR_ENCODING);
            /** 得到私钥 */
            Key privateKey = kp.getPrivate();
            byte[] privateKeyBytes = privateKey.getEncoded();
            String pri = new String(Base64Utils.encodeBase64(privateKeyBytes),
                    ConfigureEncryptAndDecrypt.CHAR_ENCODING);

            Map<String, String> map = new HashMap<String, String>();

            map.put("publicKey", pub);
            map.put("privateKey", pri);
            RSAPublicKey rsp = (RSAPublicKey) kp.getPublic();
            BigInteger bint = rsp.getModulus();
            byte[] b = bint.toByteArray();
            byte[] deBase64Value = Base64Utils.encodeBase64(b);
            String retValue = new String(deBase64Value);
            map.put("modulus", retValue);
            return map;
        }

        /**
         * 加密方法 source： 源数据
         */
        public static String encrypt(String source, String publicKey)
                throws Exception {
            Key key = getPublicKey(publicKey);

            /** 得到Cipher对象来实现对源数据的RSA加密 */
            Cipher cipher = Cipher.getInstance(ConfigureEncryptAndDecrypt.RSA_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byte[] b = source.getBytes();
            /** 执行加密操作 */
            byte[] b1 = cipher.doFinal(b);
            return new String(Base64Utils.encodeBase64(b1),
                    ConfigureEncryptAndDecrypt.CHAR_ENCODING);
        }

        /**
         * 解密算法 cryptograph:密文
         */
        public static String decrypt(String cryptograph, String privateKey)
                throws Exception {
            Key key = getPrivateKey(privateKey);
            Log.e("RSA", privateKey);

            /** 得到Cipher对象对已用公钥加密的数据进行RSA解密 */
            Cipher cipher = Cipher.getInstance(ConfigureEncryptAndDecrypt.RSA_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, key);
            byte[] b1 = Base64Utils.decodeBase64(cryptograph.getBytes());
            /** 执行解密操作 */
            byte[] b = cipher.doFinal(b1);
            return new String(b);
        }

        /**
         * 得到公钥
         *
         * @param key 密钥字符串（经过base64编码）
         * @throws Exception
         */
        public static PublicKey getPublicKey(String key) throws Exception {
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(
                    Base64Utils.decodeBase64(key.getBytes()));
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PublicKey publicKey = keyFactory.generatePublic(keySpec);
            return publicKey;
        }

        /**
         * 得到私钥
         *
         * @param key 密钥字符串（经过base64编码）
         * @throws Exception
         */
        public static PrivateKey getPrivateKey(String key) throws Exception {
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(
                    Base64Utils.decodeBase64(key.getBytes()));
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
            return privateKey;
        }

        public static String sign(String content, String privateKey) {
            String charset = ConfigureEncryptAndDecrypt.CHAR_ENCODING;
            try {
                PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(
                        Base64Utils.decodeBase64(privateKey.getBytes()));
                KeyFactory keyf = KeyFactory.getInstance("RSA");
                PrivateKey priKey = keyf.generatePrivate(priPKCS8);

                Signature signature = Signature.getInstance("SHA256WithRSA");

                signature.initSign(priKey);
                signature.update(content.getBytes(charset));

                byte[] signed = signature.sign();

                return new String(Base64Utils.encodeBase64(signed));
            } catch (Exception e) {

            }

            return null;
        }

        public static boolean checkSign(String content, String sign, String publicKey) {
            try {
                KeyFactory keyFactory = KeyFactory.getInstance("RSA");
                byte[] encodedKey = Base64Utils.decode2(publicKey);
                PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));


                Signature signature = Signature
                        .getInstance("SHA256WithRSA");

                signature.initVerify(pubKey);
                signature.update(content.getBytes("utf-8"));

                boolean bverify = signature.verify(Base64Utils.decode2(sign));
                return bverify;

            } catch (Exception e) {
                System.out.print(e);
            }

            return false;
        }

}
